This invention relates to compositions for use in the preparation of contouring, reusable glycerine-free cold packs that provide cold therapy shapeable to a curved contour of the body, and that have an improved ability to slow down temperature change while maintaining pliancy over a range of temperatures applicable to cold therapy.
The use of cold as a therapeutic treatment is as old as the practice of medicine, dating back to Hippocrates. Cold therapy helps reduce or prevent the swelling and pain that accompany musculoskeletal injuries. It can also be used to treat or prevent heat exhaustion, or for general cooling of the body. Cold""s therapeutic effects are the result of a reduction in the local metabolic activity of underlying tissues, the slowing of nerve conduction and, by its direct effect on muscle spindle activity, the reduction of muscle spasm.
Ice bags, gel packs, chemical cold packs, immersion and ice massage are the most common methods for delivering cold therapy. Each has advantages and disadvantages:
the cooling effect of ice bags lasts long, but they do not contour to the body""s curves for maximum application;
cold gel packs can be frozen and refrozen, but require greater caution because they cool the skin fast; and, like ice bags, they do not contour to the body""s curves for maximum application;
chemical cold bags are a good first-aid approach for field or wilderness, but do not produce a great degree of cold;
immersion of the foot, hand, or elbow in icy water provides complete and concentrated cold exposure, but does not lend itself to other body areas because too much of the uninjured area is exposed to the cold;
and ice massage is easy to apply and focus, but the cold tends not to penetrate deeply or last as long.
An ideal cold therapy product would, therefore, produce an effective but safe degree of cold over an extended period of time; be very flexible for maximum application to as many areas of the body as possible; and be reusable.
In addressing the demand for cold therapy products, the modern health care industry has significantly focused on gel technology. However, because the technology typically produces a gel that is a semi-solid, single mass, cold gel packs are limited in their ability to conform easily to the injured part of the body for maximum application. The industry has attempted to mitigate this limitation through innovations in packaging that enhances body fit.
A non-industry approach to contouring cold therapy is the common practice of applying a frozen pack of vegetablesxe2x80x94usually a pack of frozen peasxe2x80x94to an injured area of the body as a treatment for swelling and pain. Frozen peas, particularly, are mobile and mold into the shape of the body area treated. However, their use is limited because they cannot be frozen and unfrozen repeatedly.
The need for cold packs that address the disadvantages of limited flexibility and application, fast cooling, and limited effectiveness over an extended period of time, as well as the advantage of repeated use, remains current. A variety of approaches have been taken in an attempt to meet this need.
U.S. Pat. No. 5,129,391 to Brodsky, et al, which is incorporated herein in its entirety by reference, discloses a reusable thermal pack that, while frozen, is pliable and contours when placed against injured areas. The pack comprises uniquely shaped packaging, held in place by straps and/or fasteners, and a specially formulated gel that has a greater capacity for cold. The gel is an insoluble, colloidal, homogeneous emulsion that requires several chemicals and other specialized material. In its simplest formulation, it is made of a minimum of one light metal and a plurality of glass beads dispersed in a cellulose material. The process for preparing the gel requires many steps and includes the need for heating and controlled mixing mechanisms. The packaging is varied and complicated. For the gel to contour as effectively as possible, it must be in packs that are specially configured according to the area of the body to be treated. The teaching also discloses steps that must be taken to ensure that the gel does not accumulate in one location within packs of the invention.
U.S. Pat. No. 5,190,033 to Johnson, which is incorporated herein in its entirety by reference, teaches a reusable, cold/hot therapeutic pack that conforms to the natural contours of the body. The pack contains a plurality of thin-walled, hollow capsules containing a temperature storing substance, such as water or gel. The teaching indicates capsules manufactured of non-toxic plastic in a variety of shapes, preferably spherical in shape and one half inch or less in size. The teaching discloses that the ability to conform to the natural contours of the body is delimited by the manner of packaging. The manufacture of different sizes and shapes for application to different parts of the body is required. Because the capsules may be affected by gravity in some applications, special packaging incorporating compartments must be used in these instances. Packs of the invention also require mechanisms for the management of air in order to conform to the body part and provide maximum therapeutic benefit. In addition, manufacturing packs of the invention requires mechanisms for filling the capsules and sealing the filled capsules.
U.S. Pat. No. 5,409,500 to Dyrek, which is incorporated herein in its entirety by reference, teaches a therapeutic cold pack designed to accommodate anatomical surfaces of different sizes, shapes and locations. The pack comprises a plurality of cooling gel compartments, a distribution of predeterminedly anchored straps, and a plurality of mating fasteners on the body of the overlay and at free ends of the straps. The teaching indicates that the delivery of cold therapy to the area of the body being treated is primarily dependent upon the configuration of the pack and, only incidentally, upon the cold providing mediumxe2x80x94the cold gel. The design and manufacture of a series of cold packs is required to accommodate not just the areas of the body that contour, but all body areas as well. It is also disclosed that the composition of the cold gel is such that it remains pliant only within temperatures around 0xc2x0 C., that is, the freezing point of waterxe2x80x94again, reinforcing the need for complex, anatomical site-specific design to ensure the cold pack of the invention""s claim of versatility, accommodation and effectiveness.
U.S. Pat. No. 6,051,159 to Jie, which is incorporated herein in its entirety by reference, discloses a filling material for cold packs appropriate for laboratory, medical, industrial or home use. The filling is made of varying compositions of water, salt, glycerine and polyacrylamide that are processed in the same manner by dissolving the salt in water and mixing the solution obtained with the glycerine and polyacrylamide until a colloid forms. The resulting filling can then be packaged in a variety of ways according to the intended use. The varying compositions provide a filling material that remains flexible at temperatures no lower than xe2x88x927xc2x0 C. There is teaching that indicates that packs of the invention may become too hardened for a particular use and, thus, require softening by kneading with the hands. In addition, the filling alone does not provide maximum flexibility, but requires special packaging.
U.S. Pat. No. 6,099,555 to Sabin, which is incorporated herein in its entirety by reference, discloses a cold pack that utilizes an activatable gelling agent to increase cold persistence, better distribute cold, and more completely utilize its ingredients. To produce cold, the cold pack depends upon the negative heat of solution of a material from one zone dissolving in a liquid from another zone. There is teaching derivable from FIG. 1 of the referenced patent indicating that even though the gelling cold pack may be superior to one that is non-gelling, it still shares a property of cold produced by this method: a constant and significant increase in temperature with each passing minute. That the temperature increase is significant and, very likely, occurs more rapidly than demonstrated is further illustrated by the fact that the test involved only the cold packs"" surfaces and the ambient air. No other heat sourcexe2x80x94for example, an area of the bodyxe2x80x94is indicated. Yet the teaching states that the cold pack""s uses include the cooling of areas of the body for the purpose of treating strained muscles, joints or ligaments, or heat exhaustion. Another limitation is that the cold pack is reusable only insofar as it may be possible to configure it so that it comprises a plurality of first and/or second zones in one pack. Such a pack would then provide the option of generating negative heat of solution more than once. However, there is teaching that discloses that the preferred embodiment is a cold pack disposable after a single use. It is also disclosed that the cold pack is intended for use not only in recreational locations, but in medical facilities and households as well. A cold pack that can operate independently of a refrigerating mechanism may be economical and ecological when used in recreational locationsxe2x80x94especially in the case of field or wilderness, for example. But in terms of households and medical facilities, reusable cold packs address both economy and ecology more practicably.
The present invention provides a material that remedies several of the problems and improves upon many of the advantages presented by cold packs of the prior art. Compositions of the invention produce a smart gel that freezes like packed snow. Cold packs of the invention, therefore, fit flexibly. They contour for maximum application of cold to the injured area of the body. They can be used to treat a broad range of body areas in an uncomplicated manner. Compositions of the invention also exhibit characteristics similar to those of eutectic thermal storage solutions. They slow down temperature change and maintain a generally constant temperature. As a result, cold packs of the invention deliver an even, smooth cold that penetrates and lasts. This type of cold therapy is very beneficial for treating muscle and joint pain, swelling, sprains, and strains. Cold packs of the invention are effective over an extended period of time. They are usable more than once per freezing. Generally, cold is applied 10 to 20 minutes at a time, depending on the body area and comfort. For best results, at least 20 minutes is allowed between uses. This helps control how much an area of the body is cooled and allows the skin to return to normal temperature. A cold pack of the invention can be used at least two times within the hour from when it is first applied. Cold packs of the invention are both economical and ecological. They can be frozen and unfrozen for repeated use. They are also simple to manufacture and require only a few inexpensive and readily obtainable materials. Compositions of the invention can be cooled to the low temperatures characteristic of freezers in common use and still remain pliant. Temperatures for normal freezing range from as high as xe2x88x9212xc2x0 C. to as low as xe2x88x9216xc2x0 C.; for long period storage, normally xe2x88x9218xc2x0 C. Packs of the invention can be frozen at temperatures as low as xe2x88x9217.56xc2x0 C. and maintain pliancy.